Portable heat preservation lunch box



FIG. 1 is a perspective view of a portable heat preservation lunch box showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a back view thereof;

FIG. 4 is a left view thereof;

FIG. 5 is a right view thereof;

FIG. 6 is a top view thereof;

FIG. 7 is a bottom view thereof; and,

FIG. 8 is an open state view thereof. 

CLAIM The ornamental design for a portable heat preservation lunch box, as shown and described. 